The fences in the db duel arena have been removed, the streamer seemed to cause players to timeout for some reason so I had to remove it. I'll have to look for a new arena that isn't in a virtual world, so it will probably be somewhere over the water, out of the map.
Spectating duels has been added (only for normal duels right now). You can use /watchduel, this command gives you a camera in the middle of the arena or /watchduel ID to spectate a specific player. /stopwd is to stop watching.